Abstract

Using first-principles calculations based on density-functional theory in
its local-density approximation, we investigated the Electronic structure,
ferroelectricity and optical properties of CaBi2Ta2O9 (CBT)
for the first time. It is found that CBT compound has an indirect band gap
of 3.114 eV and the O 2s and 2p states are strongly hybridized with the 6s
states of Bi which belong to the (Bi2O2)2+ planes. The quite
strong Ta–O and Bi–O hybridization is the primary source for
ferroelectricity. Our results imply that the interaction between Bi and O is
highly covalent. The anisotropy occurs mainly above 4 eV in the optical
properties. The different optical properties have been discussed.

PACS

71.20.-b Electron density of states and band structure of crystalline solids 78.20.-e Optical properties of bulk materials and thin films